I think we have indicated here that nobody has suggested the extreme. 7 and 9 are pretty close on the chart and if you visit the web site and read the description of each, they are very similar, 7 being a bit faster…..but not that much. The only reason this should even be considered is that they are close and I have read across the various forums where carbine shooters have considered trying #7. Accurate is not going to recommend anything that might be the slightest bit risky, they will be in CYA mode.
Do the research and draw your on conclusion. If one decides not to pursue it, that will be the correct decision as well.